108 resultados para ionic liq emulsion oil sepn
Resumo:
We demonstrate an unusual shape transformation of Ag nanospheres into {111}-oriented Au–Ag dendritic nanostructures by a galvanic replacement reaction in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]).
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The electrodeposition of silver from two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) and N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide ([C4mPyr][TFSI]), and an aqueous KNO3 solution on a glassy carbon electrode was undertaken. It was found by cyclic voltammetry that the electrodeposition of silver proceeds through nucleation–growth kinetics. Analysis of chronoamperometric data indicated that the nucleation–growth mechanism is instantaneous at all potentials in the case of [BMIm][BF4] and [C4mPyr][TFSI], and instantaneous at low overpotentials tending to progressive at high overpotentials for KNO3. Significantly, under ambient conditions, the silver electrodeposition mechanism changes to progressive nucleation and growth in [C4mPyr][TFSI], which is attributed to the uptake of atmospheric water in the IL. It was found that these differences in the growth mechanism impact significantly on the morphology of the resultant electrodeposit which is characterised ex situ by scanning electron microscopy and X-ray diffraction.
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The effect of storage time on the cyclability of lithium electrodes in an ionic liquid electrolyte, namely 0.5 m LiBF4 in N-methyl-N-propyl pyrrolidinium bis(fluorosulfonyl)imide, [C3mpyr+][FSI–], was investigated. A chemical interaction was observed which is time dependent and results in a morphology change of the Li surface due to build up of passivation products over a 12-day period. The formation of this layer significantly impacts on the Li electrode resistance before cycling and the charging/discharging process for symmetrical Li|0.5 m LiBF4 in [C3mpyr+][FSI–]|Li coin cells. Indeed it was found that introducing a rest period between cycling, and thereby allowing the chemical interaction between the Li electrode and electrolyte to take place, also impacted on the charging/discharging process. For all Li surface treatments the electrode resistance decreased after cycling and was due to significant structural rearrangement of the surface layer. These results suggest that careful electrode pretreatment in a real battery system will be required before operation.
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The effect of extended cycling on lithium metal electrodes has been investigated in an ionic liquid electrolyte. Cycling studies were conducted on lithium metal electrodes in a symmetrical Li|electrolyte|Li coin cell configuration for 5000 charge–discharge cycles at a current density of 0.1 mA cm− 2. The voltage–time plots show evidence of some unstable behavior which is attributed to surface reorganization. No evidence for lithium dendrite induced short circuiting was observed. SEM imaging showed morphology changes had occurred but no evidence of needle-like dendrite based growth was found after 5000 charge–discharge cycles. This study suggests that ionic liquid electrolytes can enable next generation battery technologies such as rechargeable lithium-air, in which a safe, reversible lithium electrode is a crucial component.
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We demonstrate for the first time the ionic-liquid-mediated synthesis of nanostructured CuTCNQ by the simple immersion of copper in a solution of TCNQ where the viscosity of the medium significantly impacts the corrosion–crystallization process and the final morphology of the material.
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The topic of “the cloud” has attracted significant attention throughout the past few years (Cherry 2009; Sterling and Stark 2009) and, as a result, academics and trade journals have created several competing definitions of “cloud computing” (e.g., Motahari-Nezhad et al. 2009). Underpinning this article is the definition put forward by the US National Institute of Standards and Technology, which describes cloud computing as “a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction” (Garfinkel 2011, p. 3). Despite the lack of consensus about definitions, however, there is broad agreement on the growing demand for cloud computing. Some estimates suggest that spending on cloudrelated technologies and services in the next few years may climb as high as USD 42 billion/year (Buyya et al. 2009).
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Few would argue that the upstream oil & gas industry has become more technology-intensive over the years. But how does innovation happen in the industry? Specifically, what ideas and inputs flow from which parts of the sector’s value network, and where do these inputs go? And how do firms and organizations from different countries contribute differently to this process? This paper puts forward the results of a survey designed to shed light on these issues. A joint research initiative between the Society of Petroleum Engineers and the Queensland University of Technology, the survey was sent to 469 executives and senior managers who played a significant role with regards to R&D and/or technology deployment in their respective business units. A total of 199 responses were received from a broad range of organizations and countries around the world. Several interesting themes and trends emerge from the results, including: (1) service companies tend to file considerably more patents per innovation than other types of organization; (2) over 63% of the deployed innovations reported in the survey originated in service companies; (3) neither universities nor government-led research organizations are considered to be valuable sources of new information and knowledge in the industry’s R&D initiatives; and (4) despite the increasing degree of globalization in the marketplace, the USA still plays an extremely dominant role in the industry’s overall R&D and technology deployment activities. By providing a detailed snapshot of how innovation happens in the upstream oil & gas sector, this paper provides a valuable foundation for future investigations and discussions aimed at improving how R&D and technology deployment are managed within the industry.
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Many alternative therapies are used as first aid treatment for burns, despite limited evidence supporting their use. In this study, Aloe vera, saliva and a tea tree oil impregnated dressing (Burnaid) were applied as first aid to a porcine deep dermal contact burn, compared to a control of nothing. After burn creation, the treatments were applied for 20 min and the wounds observed at weekly dressing changes for 6 weeks. Results showed that the alternative treatments did significantly decrease subdermal temperature within the skin during the treatment period. However, they did not decrease the microflora or improve re-epithelialisation, scar strength, scar depth or cosmetic appearance of the scar and cannot be recommended for the first aid treatment of partial thickness burns.
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This paper uses examples from the history and practices of multi-national and large companies in the oil, chemical and asbestos industries to examine their legal and illegal despoiling and destruction of the environment and impact on human and non-human life. The discussion draws on the literature on green criminology and state-corporate crime and considers measures and arrangements that might mitigate or prevent such damaging acts. This paper is part of ongoing work on green criminology and crimes of the economy. It places these actions and crimes in the context of a global neo-liberal economic system and considers and critiques the distorting impact of the GDP model of ‘economic health’ and its consequences for the environment.
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Frequency Domain Spectroscopy (FDS) is used to assess the insulation condition of oil-paper power transformers. Dissipation factor is one of the conventional indicators to analyze insulation ageing status. In this paper, the imaginary admittance of the transformers insulation, after removal of the geometric capacitance, is proposed as an alternative indicator to assist in the interpretation of ageing status. Ageing effects on the imaginary admittance are investigated both through simulation results and experimental results.
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Much of what we currently understand about the structure and energetics of multiply charged anions in the gas phase is derived from the measurement of photoelectron spectra of simple dicarboxylate dianions. Here we have employed a modified linear ion-trap mass spectrometer to undertake complementary investigations of the ionic products resulting from laser-initiated electron photodetachment of two model dianions. Electron photodetachment (ePD) of the \[M-2H](2-) dianions formed from glutaric and adipic acid were found to result in a significant loss of ion signal overall, which is consistent with photoelectron studies that report the emission of slow secondary electrons (Xing et al., 2010 \[201). The ePD mass spectra reveal no signals corresponding to the intact \[M-2H](center dot-) radical anions, but rather \[M-2H-CO2](center dot-) ions are identified as the only abundant ionic products indicating that spontaneous decarboxylation follows ejection of the first electron. Interestingly however, investigations of the structure and energetics of the \[M-2H-CO2](center dot-) photoproducts by ion-molecule reaction and electronic structure calculation indicate that (i) these ions are stable with respect to secondary electron detachment and (ii) most of the ion population retains a distonic radical anion structure where the radical remains localised at the position of the departed carboxylate moiety. These observations lead to the conclusion that the mechanism for loss of ion signal involves unimolecular rearrangement reactions of the nascent \[M-2H](center dot-) carbonyloxyl radical anions that compete favourably with direct decarboxylation. Several possible rearrangement pathways that facilitate electron detachment from the radical anion are identified and are computed to be energetically accessible. Such pathways provide an explanation for prior observations of slow secondary electron features in the photoelectron spectra of the same dicaboxylate dianions. (C) 2013 Elsevier B.V. All rights reserved.
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The dicoordinated borinium ion, dihydroxyborinium, B(OH)(2)(+) is generated from methyl boronic acid CH3B(OH)(2) by dissociative electron ionization and its connectivity confirmed by collisional activation. Neutralization-reionization (NR) experiments on this ion indicate that the neutral B(OH)(2) radical is a viable species in the gas phase. Both vertical neutralization of B(OH)(2)(+) and reionization of B(OH)(2) in the NR experiment are, however, associated with particularly unfavorable Franck-Condon factors. The differences in adiabatic and vertical electron transfer behavior can be traced back to a particular pi stabilization of the cationic species compared to the sp(2)-type neutral radical. Thermochemical data on several neutral and cationic boron compounds are presented based on calculations performed at the G2 level of theory.
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Biodiesel derived from microalgae is one of a suite of potential solutions to meet the increasing demand for a renewable, carbon-neutral energy source. However, there are numerous challenges that must be addressed before algae biodiesel can become commercially viable. These challenges include the economic feasibility of harvesting and dewatering the biomass and the extraction of lipids and their conversion into biodiesel. Therefore, it is essential to find a suitable extraction process given these processes presently contribute significantly to the total production costs which, at this stage, inhibit the ability of biodiesel to compete financially with petroleum diesel. This study focuses on pilot-scale (100 kg dried microalgae) solvent extraction of lipids from microalgae and subsequent transesterification to biodiesel. Three different solvents (hexane, isopropanol (IPA) and hexane + IPA (1:1)) were used with two different extraction methods (static and Soxhlet) at bench-scale to find the most suitable solvent extraction process for the pilot-scale. The Soxhlet method extracted only 4.2% more lipid compared to the static method. However, the fatty acid profiles of different extraction methods with different solvents are similar, suggesting that none of the solvents or extraction processes were biased for extraction of particular fatty acids. Considering the cost and availability of the solvents, hexane was chosen for pilot-scale extraction using static extraction. At pilot-scale the lipid yield was found to be 20.3% of total biomass which is 2.5% less than from bench scale. Extracted fatty acids were dominated by polyunsaturated fatty acids (PUFAs) (68.94±0.17%) including 47.7±0.43 and 17.86±0.42% being docosahexaenoic acid (DHA) (C22:6) and docosapentaenoic acid (DPA) (C22:5, ω-3), respectively. These high amounts of long chain poly unsaturated fatty acids are unique to some marine microalgae and protists and vary with environmental conditions, culture age and nutrient status, as well as with cultivation process. Calculated physical and chemical properties of density, viscosity of transesterified fatty acid methyl esters (FAMEs) were within the limits of the biodiesel standard specifications as per ASTM D6751-2012 and EN 14214. The calculated cetane number was, however, significantly lower (17.8~18.6) compared to ASTM D6751-2012 or EN 14214-specified minimal requirements. We conclude that the obtained microalgal biodiesel would likely only be suitable for blending with petroleum diesel to a maximum of 5 to 20%.
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This project was a step forward in developing a 'descriptive theory' of contracting in the oil and gas industry that reflects the operating environment in which the project manager operates. This study investigates the existing processes and methods used in establishing contracts which are very often prescriptive, and not always appropriate or optimal for a given situation. This study contributes to contracting effectiveness or optimal contracting in the oil and gas industry.
Resumo:
Neutral NCN is made in a mass spectrometer by charge stripping of NCN-., while neutral dicyanocarbene NCCCN can be formed by neutralization of either the corresponding anionic and cationic species, NCCCN-. and NCCCN+.. Theoretical calculations at the RCCSD(T)/aug-cc-pVTZ//B3LYP/6-31+G(d) level of theory indicate that the (3)Sigma (-)(g) State of NCCCN is 18 kcal mol(-1) more stable than the (1)A(1) state. While the majority of neutrals formed from either NCCCN-. or NCCCN+. correspond to NCCCN, a proportion of the neutral NCCCN molecules have sufficient excess energy to effect rearrangement, as evidenced by a loss of atomic carbon in the neutralization reionization (NR) spectra of either NCCCN+. and NCCCN-.. C-13 labeling studies indicate that loss of carbon occurs statistically following or accompanied by scrambling of all three carbon atoms. A theoretical study at the B3LYP/6-31+G(d)//B3LYP/6-31+G(d) level of theory indicates that C loss is a consequence of the rearrangement sequence NCCCN --> CNCCN --> CNCNC and that C scrambling occurs within singlet CNCCN via the intermediacy of a four-membered C-2v-symmetrical transition structure.